1. Field of the Invention
The present invention relates to control for an automated mechanical transmission system and in particular to a control for selecting, as a function of sensed system operating parameters, either (i) a shift sequence involving master clutch disengagement or (ii) a shift sequence not involving master clutch disengagement, in an automatic mechanical transmission system including an automated master friction clutch.
2. Description of the Prior Art
Automate mechanical transmission systems (i.e., systems having transmissions wherein gear ratios are engaged and disengaged by jaw clutches) having automated master clutch operators are known in the prior art as may be seen by reference to U.S. Pat. Nos. 4,081,065; 4,361,060; 4,648,290; 4,936,428; 5,960,916; 5,947,847; and 5,634,867, the disclosures of which are incorporated herein by reference. Automated mechanical transmission systems not having an automatic master clutch actuator and requiring manual master clutch operation, usually only to launch the vehicle, are also known in the prior art as may be seen by reference to U.S. Pat. Nos. 6,145,399; 5,582,558; 6,146,310; 5,272,939; 5,335,566; and 5,425,689, the disclosures of which are incorporated herein by reference.
The prior art automated transmissions systems not having an automated master clutch actuator, by necessity, utilized a shift sequence for dynamic automatic shifting not requiring disengagement of the vehicle master clutch. Typically, engine fueling was controlled to relieve torque lock, allowing a shift from a previously engaged ratio into neutral and then the engine was caused to rotate at a substantially synchronous speed for engaging a target ratio, all with the master clutch remaining engaged. Systems of this type may be seen by reference to U.S. Pat. Nos. 4,850,263; 5,820,104; 4,593,580; 5,582,558; 6,126,570; and 6,145,399, the disclosures of which are incorporated herein by reference.
The prior art automated mechanical transmission systems having an automated master clutch actuator tended to utilize a shift strategy or sequence for all dynamic shifts which included disengaging and then re-engaging the master friction clutch at least once during each shift, regardless if that shift could have been acceptably and/or preferably performed without disengaging and re-engaging the master clutch.